Rear lamps of motor vehicles are subject to the requirement that the emitted light beams should form various patterns that produce a spatial effect both in the lit up state and in the off state. Fulfillment of variable requirements is achieved by using of a number of LED light sources where its own reflector is assigned to each LED source. However, a high number of LED sources is inconvenient because LED sources must be laboriously adjusted and therefore it is desirable to restrict the number of LED sources. A restricted number of LED light sources conversely limits production of light effects.
The document DE102011002281 describes a lamp for motor vehicles with a light source consisting of a LED source and a flat light guide assigned to it that is arranged transversally to the optical axis of the lamp. The light source is arranged at one flat side of the light guide in its central part against the entry surface through which the light beams enter the light guide. A fully reflective surface is arranged against the entry surface in the central part of the light guide, the reflective surface deflecting the light beams emitted from the light source in the transversal direction to the optical axis of the lamp towards the marginal part of the light guide. In the marginal area distant from the optical axis, the flat light guide has another fully reflective surface to deflect the unbound light beam back in the direction of the optical axis, of the lamp. For exit of the light beam in the direction of the optical axis on its other flat side in the marginal area distant from the optical axis, the light guide has a light unbinding surface to unbind the light beam in the direction of the optical axis of the lamp. Thus, the fully reflective surfaces of the flat light guide first reflect the light beam in the radial direction, transversally to the optical axis A, and then, in an offset way, from the optical axis back in the direction that is parallel to the optical axis. One light source is assigned to the light guide. The light emitted around the perimeter of the flat light guide in the direction of the optical axis of the lamp produces a light curve of a shape corresponding to the shape of the flat light guide. However, inside this light curve there is a dark space through which no light is emitted from the light guide. Thus, a single light curve can be produced by one light guide, and to produce another light curve another flat light guide arranged in parallel to the first light guide must be used. The light guides can only be combined in a limited way because other light guides can only be added in such a manner that their light curves lie concentrically inside the light curve of the previous light guide, or completely apart from each other. A lamp with more light curves would be too voluminous, heavy, costly and impractical.
The document DE102010045052 discloses a light device designed to create a supplementary side signal light, additionally to the main tail light or brake light of the motor vehicle. The light device comprises a light source with a flat light guide assigned to it, having a light entry surface for the introduction of the light. The opposite large sides of the flat light guide totally reflect the introduced light in such a way to make it move forward through the flat light guide to its end at the opposite side with regard to the entry surface. At the end of the light guide there is an exit surface to unbind light from the light guide. The entry introductory surface and the exit unbinding surface are each created at the thin sides of the light guide. The exit surface is inclined and partly reflects the light beam in the transversal direction to the large side of the light guide, and the remaining part of the light beam passes through the inclined exit surface in the direction of direct propagation of light from the light source. The light exit surface can be made of two parts, so that the first part of the exit surface is inclined obliquely to the direction of direct propagation of light from the light source, and the other part of the exit surface is perpendicular to the direction of direct propagation of light from the light source. The first partial beam reflects from the inclined first part of the exit surface, exits transversally to the direction of direct propagation of light from the light sources and provides the first light function, and the other partial beam passes through the other part of the exit surface and provides another light function. The direction of direct propagation of light from the light source is equal to the longitudinal axis of the motor vehicle. Thus, the light device can create two light beams that are transversally inclined with regard to each other. The first function may be the directional light indicator and the other function may be the tail light. In the direction of the longitudinal axis of the motor vehicle, the light beam only exits from the light device through the thin side of the flat light guide, the size of which is limited. The length of the light guide in the longitudinal direction of the motor vehicle increases the depth of the bushing of the light device. If the flat light guide is arranged perpendicularly to the longitudinal axis of the motor vehicle, the light beam emitted in the direction of the longitudinal axis of the motor vehicle is limited by the size of the reflective surface of the light guide. If the light guides are arranged linearly in the longitudinal axis direction, the total depth of the light device bushing increases.
The document DE19652159 discloses a signal lamp that comprises an L-shaped light guide and a light source the light of which enters the light guide through the front surface of one arm of the light guide and exits from the light guide through the peripheral surface of the other arm of the light guide. The other arm of the light guide is made of glass or plastic, especially PMMA, polymethyl methacrylate, or polycarbonate, and on the casing surface it is fitted with an area from which a part of the light passing through the light guide exits. The light guide can be arranged in the lamp casing or along the edge of the lamp bushing, either inside or outside the lamp bushing so as not to influence the main light beam exiting from the lamp. The light guide can run along the whole perimeter of the lamp and it can generally have a curved shape, e.g. circular. The light guide arms, arranged perpendicularly to each other, can be connected with a rounded transition piece. The entry part of the light guide can consist of two separated light guides, out of which the first light guide forms the first arm connected to the perpendicularly arranged second arm by means of a rounded transitional piece. The second light guide of a cylindrical shape runs in parallel with the first arm of the first light guide, and in the area of the rounded transition between the first and second arm the second light guide opens out into the exit surface fitted with optical elements and in the light exit direction covering the rounded transition between the first and second arm. The exit area of the second light guide is larger than the size of the cross-section of the second light guide. The first light guide can form a nearly closed flat pattern of a rectangular shape, the neighbouring sides of which are connected to each other with a transition of a broken shape. A disadvantage of the arrangement of the first light guide in accordance with the document DE19652159 is its flat arrangement, which only makes it possible to use the light guide around the perimeter of the main lamp. Another disadvantage is the fact that in the rounded transition and broken transition between the neighbouring, mutually perpendicularly arranged arms of the light guide, the intensity of the luminous flux passing from one arm to the next arm is reduced.
The goal of the invention is to provide a signal lamp, especially a rear lamp for motor vehicles that actively produces light patterns with a spatial effect in the lit up state and in the off state maintains a spatial impression, produces a clear light outline, requires a small number of LED light sources to fulfil its function, has compact dimensions, and can be produced easily and at low costs.